It could be a ‘La Nada’ type of winter in California, say climatologists

It could be a ‘La Nada’ type of year, say climatologists

By Steve Scauzillo, Los Angeles News Group

Sunday, September 10, 2017

After suffering more than a week under searing, desert-like heat, winter might be the furthest thing from the minds of most Californians.

However, to borrow a phrase from TV’s “Game of Thrones,” winter is coming.

The only question is whether the gods will allow a rerun of last winter which unexpectedly dumped record amounts of rain and snow throughout the state that filled reservoirs and kept skiers on the slopes through August.

Several climate experts, flummoxed by the failure of a widely predicted El Niño to make a dent in California’s drought during the winter of 2015-16, are saying they are unsure what this winter will bring.

The National Oceanic and Atmospheric Administration says December-January-February in California will be a winter with equal chances of normal, below normal and above normal rain.

“That means they do not know. There is no strong signal,” said Bill Patzert, the expert climatologist from NASA’s Jet Propulsion Laboratory in La Cañada Flintridge, who incorrectly predicted tons of rain from the “Godzilla El Niño” for the 2015-2016 winter.

For this coming winter, however, with no El Niño in sight, he’s making a not-so-bold prediction: It’s going to be either wet or dry.

To be fair, Patzert’s prediction was true for Northern California and Texas. If it weren’t for a stubborn ridge of high pressure pushing the Jet Stream storms north and south of Los Angeles, he would have been accurate.

The fact that Los Angeles received 131 percent of average rainfall the following winter — Oct. 1, 2016 through April 30 — and the Sierra Nevada received record levels of snowpack is inexplicable, he said.

“Either we slip back into drought or we have a repeat of last winter,” Patzert said.

Ken Clark, expert meteorologist with AccuWeather.com, who has been studying the state’s weather patterns since 1996, took a stab at predicting upcoming winter weather.

“We are looking at more of a moderate winter with a decent amount of storms, perhaps better if you go farther north than south (in California). But a decent amount of precipitation,” he said.

The region will not slip back into drought, Clark said.

When pushed, he leaned more toward wet, atmospheric river storms being the star of a Southern California winter.

Why the wetter guesstimate?

He’s talked to the fisherman in Orange County and San Diego, who say warmer ocean temperatures have conjured up species of fish seen only in warmer, southern waters. Some have caught blue marlin off the Southern California coast, he said.

Warm Pacific waters adds vapor to a storm. And like gasoline added to a fire, this broadens the storm’s size and intensity.

Andreas Prein, atmospheric scientist at the National Center for Atmospheric Research in Boulder, Colorado, released a study in 2015 that said the Southwest, and especially California, are seeing fewer storms and higher temperatures. Fewer storms point to a drier climate, i.e. more droughts, he said.

But even with fewer storms slashing the state, warmer ocean and air temperatures could make each storm stronger, packing stronger winds and rain, Prein’s report said. Last winter, narrow bands of water extending from the Pacific Ocean drenched Southern California. These storms are what meteorologists call atmospheric river events.

Overall, his study is not good news for a state that needs rainfall and snowpack to quench the thirst of nearly 40 million people, not to mention irrigation for the farms which feed millions of people and support a $47 billion industry.

But the state could get lucky.

“Instead of five atmospheric river events, you get only three, but those three are significant,” Prein supposed during an interview. “As you saw last winter, the atmospheric rivers can have devastating effects on our infrastructure,” he said, referring to estimates of $1 billion in damage to levees, bridges, dams and roads.

“Only a few can take you from a dry year to a wet year,” Prein said.

Of course, frequent rain storms and deep snowpack don’t solve California’s water storage problems. About 85 percent of the storm water in the Los Angeles River drains to the ocean. The San Gabriel and Santa Ana rivers have much greater water-capturing abilities, using rubber dams to pool water and let it sink into underground aquifers through soft, permeable river bottoms.

About the only thing meteorologists interviewed agree on was that the state is getting warmer. Climate change, involving the trapping of heat from the burning of fossil fuels, has raised the average winter temperature in the state 2.5 degrees Fahrenheit over the last 100 years, Patzert said.

“Heat waves are more intense. They last longer. That has been measured. We know that California winters are warmer and the snowpack comes later and leaves earlier. That is a trend, not a forecast,” Patzert said.

Patzert and Prein agree that the warming of the oceans, the melting ice caps, the changes to the Jet Stream and the size of high pressure systems — all related to climate change — tell more about California winters than El Niño or the opposite, La Niña, or the current neutral system that Patzert calls “La Nada.”

“All this has as big of an impact as to whether we have a La Niña or El Niño,” Patzert said. Prein said climate change adds another layer of complexity to long-range weather forecasting.

“We are disturbing the natural system. It is an additional variable,” he said.